1. Field of the Invention
The present invention relates to an anthracene compound for an organic electroluminescent device, and more particularly to an anthracene compound serving as a light-emitting layer or hole transport layer of an organic electroluminescent device.
2. Description of the Related Art
An organic electroluminescent device (also referred to as organic light-emitting diode; OLED) is an LED with an organic layer acting as the active layer, increasingly applied in flat panel displays due to advantages, such as low voltage operation, high brightness, light weight, slim profile, wide viewing angle, and highly effective contrast ratio.
Generally, an OLED is composed of a light-emitting layer and a pair of electrodes sandwiching the light-emitting layer. Light emission is caused by the following phenomenon. When an electric field is applied to these two electrodes, the cathode injects electrons into the light-emitting layer and the anode injects holes into the light-emitting layer. When the electrons recombine with the holes in the light-emitting layer, their energy level shifts to a valence bond band which causes them to release energy as fluorescent light.
Anthracene has been used as material for a hole transport layer and a light-emitting layer. For example, U.S. Pat. No. 6,465,115 discloses an organic anthracene material as the hole transport layer, having the following formula:

wherein Ar is individually substituted or unsubstituted aryl having 5 to 20 carbon atoms.
In U.S. Pat. No. 5,759,444, an anthracene compound emitting light is disclosed, having the following formula:

wherein each of A1 to A4 is a substituted or unsubstituted aryl group having 6 to 16 carbon atoms. In the anthracene compound, the diarylamino group is introduced at positions 9 and 10 of the anthracene ring. It is found that the diarylamino group causes the anthracene light-emitting material to have a hole transport property. In addition, the stability at the interface between the light-emitting layer and the hole transport layer is increased, thus increasing the life of the device.